Railway Science (Physics-Force and Pressure) (Part-III)

Total Questions: 50

11. The momentum of a moving object depends on some factors. Which of the following statements is most appropriate? [RRB Group D 1/12/2018 (Afternoon)]

Correct Answer: (b) The momentum of a moving object depends on its mass and velocity.
Solution:

Momentum is a vector quantity. Its formula is; p = m × v. (Where p - momentum, m - mass, and v - velocity).

12. Positive acceleration means ______. [RRB Group D 4/12/2018 (Afternoon)]

Correct Answer: (c) velocity of a body increases
Solution:

Acceleration is defined as the rate of change of velocity. Negative acceleration means velocity of a body is decreasing. Uniform acceleration - When an object is traveling in a straight line with an increase in velocity at equal intervals of time. No acceleration means no change in velocity.

13. The velocity of a ball thrown vertically with time will be: [RRB Group D 4/12/2018 (Evening)]

Correct Answer: (d) positive upwards
Solution:

This is because at the moment of throwing, the ball has a positive velocity in the upward direction. Velocity: The rate of change of the position or displacement of an object with time. Velocity = 𝑑𝑖𝑠𝑝𝑙𝑎𝑐𝑒𝑚𝑒𝑛𝑡/𝑡𝑖𝑚e .

14. Which of the following is the effect of a balanced force applied to an object? [RRB Group D 4/12/2018 (Evening)]

Correct Answer: (d) change in speed of an object
Solution:

If an unbalanced force is applied on the object, there will be a change either in its speed or in the direction of its motion. Thus, to accelerate the motion of an object, an unbalanced force is required.

15. In a confrontation _____ is always saved. [RRB Group D 05/12/2018 (Morning)]

Correct Answer: (c) momentum
Solution:

product of the mass of a particle and its velocity. It has both direction and magnitude and the SI unit is kilogram-metre per second (kg m s -1). Force: This is an external agent capable of changing a body's state of rest or motion. SI unit - newton.

16. The total quantity of motion contained in the same body is called ______. [RRB Group D 06/12/2018 (Morning)]

Correct Answer: (c) momentum
Solution:

(Kg.m/s) - mass × Velocity. Physical Quantity and Formula : Speed (m/s) = Distance/Time. Velocity (m/s) = Displacement/time. Acceleration (m/s2 ) = Change in Velocity/Change in time. Force (Newton) = mass × acceleration. Kinetic Energy (Joule) = 1/2 mv². Potential Energy (Joule) = mgh. Power (watt) = VI, I²R, 𝑉²/R.

17. The pressure exerted by a solid decreases with increase in ______. [RRB Group D 07/12/2018 (Morning)]

Correct Answer: (b) area
Solution:

SI unit is square metre (m²). Force: The push or pull on an object with mass causes it to change its velocity. SI unit - newton (N). 1 N = kg m/s².

18. If the velocity of an object is proportional to the time elapsed, then the velocity of the object will be __________. [RRB Group D 07/12/2018 (Evening)]

Correct Answer: (b) uniform acceleration
Solution:

19. Zero acceleration means ______. [RRB Group D 12/12/2018 (Morning)]

Correct Answer: (a) body has constant velocity
Solution:

Zero acceleration means an object's velocity is not changing. If the change in velocity is zero i.e. either the object is at rest or moving with uniform velocity then the object is said to have zero acceleration.

20. Pressure is defined as _______. [RRB Group D 12/12/2018 (Morning)]

Correct Answer: (d) Thrust per unit area
Solution:

Pressure is defined as the force divided by the area perpendicular to the force over which the force is applied, or P = F/A. The SI unit for pressure is the pascal, where 1 Pa = 1 N/m².